1. Field of the Invention
The present invention generally relates to lawn mowers, and more particularly concerns lawn mowers of the type that are capable of use in a mode where the operator rides upon the lawn mower and, in addition, in a mode where the operator walks along with the lawn mower.
2. Description of the Prior Art
The array of available lawn mowers includes a wide variety of devices where the operator rides upon the lawn mower, and devices where the operator walks with the mower.
Riding lawn mowers typically have an internal combustion engine mounted to a chassis, and coupled to a grass cutting deck attached below the chassis, with an operator's seat attached upon the chassis. Where the riding mower is of the zero-turning radius type, a pair of caster type front wheels may be supplied along with a pair of rear wheels, each rear wheel attached to a variable speed reversible transmission, such as a hydrostatic transmission, the transmissions coupled to the engine. By separately controlling each of the transmissions, drive to the rear wheels is supplied, providing both propulsion and steering for the lawn mower. Walking lawn mowers typically have an internal combustion engine mounted to a chassis with a grass cutting deck coupled to the engine, and may, in a manner similar to riding mowers, have separately controllable hydrostatic transmissions and rear wheels.
In various circumstances, it is desirable that a lawn mower be capable of operation in both a riding mode and a walking mode. For mowing large, uninterrupted expanses, a riding lawn mower is generally appropriate in order to increase efficiency and reduce operator fatigue. On the other hand, where vertical clearance is limited, for instance near low trees and similar obstacles, operation of a lawn mower in a walking mode is most advantageous.
There are presently available a number of lawn mowers that are described as capable of use in both such modes, that is, the operator may ride upon the lawn mower, or, alternatively, the operator may walk along with the lawn mower. One such device is described in U.S. Pat. No. 5,307,612, where a generally curved L-shaped handle post may be pivoted between a first position where the horizontal portion of the handle post is proximate to a seat, and a second position where the horizontal portion is disposed behind the lawn mower. In both positions, the lawnmower is operated by squeeze-type control levers actuating control wires disposed through the curved handle post. In lawn mowers of this type, while the controls may operate as intended when the curved handle post in disposed in either the walking or riding configuration, after the curved handle post has been rotated for operation in the other mode, the control wires may bind or go out of adjustment. As a result, for instance, when the control levers are apparently disposed in a neutral position, the transmissions of the lawn mower may not actually be in a neutral position, with the result that the lawn mower may move forward or backward contrary to the desire and at the peril of the operator. In addition, after a long period of use, operator fatigue with respect to repeated activation of the control levers may become a significant problem. In another device, described by U.S. Pat. No. 5,355,661, separate control portions are provided for use in the riding mode and in the walking mode, with a control prohibiting device for alternatively preventing operation of one of the control portions. By pivoting through approximately 30 degrees about a transverse axis, a steering handle is moved from a rear position for the walking mode to a front position where an arm attached to the front of the steering handle is used in the riding mode.
Despite the availability of such lawn mowers, there exists a need in the art for a lawn mower that is capable of use in both a riding mode and a walking mode, yet has a relatively simple, robust and easily serviced control system for variable speed reversible transmissions that is capable of reliable use with a minimum of physical effort.